I LOVE the characters in this; they have really great chemistry and it seems like they're all doing their own thing, which is great. My only advice would be to make them a little less... typical. In a main character, predictability is great, actually, but in characters like Jason especially, I think we need to see a little more "moroseness" if you get my drift... he seems a bit too mundane. Give him more dry humor and wait a while in the plot before introducing his passion for Katie. I adore the development of the overall plot so far, though, and I can't wait to see where this goes!